Efficiency of the fluidized-bed catalytic ozonation process on the treatment of high salinity organic wastewater

Treatment of high salinity organic wastewater by catalytic ozonation is challenging because inorganic (such as SO₄²⁻) inhibit the catalytic ozonation efficiency, particularly in conventional fixed-bed reactors. Despite their widespread application, fixed-bed reactors are vulnerable to salt-induced catalyst deactivation and exhibit sub-optimal low mass transfer efficiency. This study systematically compared the performance of fixed-bed and fluidized-bed catalytic ozonation under high salinity (5–20 g/L Na 2 SO 4 ) and revealed the anti-salt mechanism driven by intensified gas-liquid-solid contact dynamics in the fluidized-bed. Under these saline conditions, the specific TOC removal efficiency ( η TOC ) fell to 0.54–0.60 in the fixed‑bed but remained as high as 0.97–1.08 in the fluidized‑bed, indicating that the latter maintains stable performance under high salt conditions despite its lower catalyst adsorption capacity (3.627 g/(mg·min) for the fluidized-bed vs. 8.445 g/(mg·min) for the fixed-bed). Notably, at 10 g/L Na₂SO₄, the fluidized-bed achieved a 14.12 % higher TOC removal and 10.93 % greater fluorescence organic matter degradation than under salt-free conditions. This superior performance is attributed to mitigated sulfate adsorption and preservation of catalytic active sites. The findings support the potential of fluidized-bed catalytic ozonation as a sustainable, cost-effective, and robust approach for treating high salinity organic wastewater.